Electromagnetic switching device utilizing stray magnetic flux

ABSTRACT

This invention relates to electromagnetic devices for driving electric switches or various mechanical means such as a ratchet or a valve. The electromagnetic device of the present invention comprises at least one winding for generating magnetic flux, one stator core magnetically coupled with the said winding, and a movable armature which is attracted to the core when the magnetic flux is generated; and is characterized in that at least one magnetically responsive switching means for controlling the said magnetic flux upon receiving stray magnetic flux is provided in a position where the said switching means receives the stray magnetic flux developed by existence of a gap or gaps between the armature and the stator core. The electromagnetic device of the present invention can be made considerably smaller in size as well as requiring a smaller driving current than conventional devices, and has higher reliability. A delayed set operation is easily obtainable in the electromagnetic device of this invention.

United States Patent Inventors Sliigeru Tanimura Fushimi-ku; Kenzo Kamei, Inuyama, Japan Appl. No. 819,281 Filed Apr. 25, 1969 Patented Mar. 2, I971 Assignee Omron Tateisi Electronic Co.

Ukyo-ku, Kyoto, Japan Priority Apr. 25, 1968 Japan 43-28096 ELECTROMAGNETIC SWITCHING DEVICE UTILIZING STRAY MAGNETIC FLUX Primary Examiner-James D. Trammell Assistant Examiner-Harvey F endelman Attorney-Craig, Antonelli, Stewart& Hill ABSTRACT: This invention relates to electromagnetic devices for driving electric switches or various mechanical means such as a ratchet or a valve.

The electromagnetic device of the present invention comprises at least one winding for generating magnetic flux, one stator core magnetically coupled with the said winding, and a movable armature which is attracted to the core when the magnetic flux is generated; and is characterized in that at least one magnetically responsive switching means for controlling the said magnetic flux upon receiving stray magnetic flux is provided in a position where the said switching means receives the stray magnetic flux developed by existence of a gap or gaps between the armature and the stator core.

The electromagnetic device of the present invention can be made considerably smaller in size as well as requiring a smaller driving current than conventional devices, and has higher reliability. A delayed set operation is easily obtainable in the electromagnetic device of this invention.

PATENTEDMAR 2191: 3568;008

sum urz INVENTORS SHIGE 1w TA NI'M RA ,nwzo KAMEI' ELECTROMAGNETIC SWITCHING DEVICE UTILIZING STRAY MAGNETIC FLUX This invention relates to an electromagnetic device for driving electric switches or various mechanical means such as a ratchet or a valve. More particularly, this invention relates to an electromagnetic device which takes larger current when driving its armature from its rest position to its set position and takes smaller current when keeping the armature in its set position.

As is known, an electromagnetic device requires a large number of ampere turns when driving its armature from rest position to a set positionand requires a smaller number of ampere turns to keep the armature in the set position. where the armature touches a core. Accordingly, conventional electromagnetic devices are so constituted that their ampere turns can be reduced to a'small value after the armature reaches the set position.'Such conventional devices require a pair of additional switch contacts which switch the circuit so that a current-restricting resistor is connected in series to the winding just after the setting of the device, or so that an auxiliary winding providedfor adding the necessary additional ampere turns to achieve the setting of the switch is disconnected after the setting of the device. Provision of these additional switch contacts inevitably causes an increase of ampere turns necessitated by additional feeding of contact pressure to the additional switch contacts, resulting in an increase in the operating power and the size of the device. Moreover, such additional switch contacts require delicate adjustment in order to properly reduce the ampere turns just after the setting of the device. Such delicate adjustment of the contacts is hardly feasible nor does it ensure stable operation.

One object of the present invention is to provide an improved electromagnetic device excluding the above-mentioned shortcomings of conventional devices. 1

A further object of this invention is to provide an improved electromagnetic device capable of a delayed set operation.

The electromagnetic device of the present invention comprises at least one winding for generating magnetic flux, a stator core magnetically coupled with the said winding, and a movable armature which is attracted to the core when the magnetic flux is generated; and is characterizedin that at least a magnetically responsive switching means, for controlling the said magnetic flux upon receiving stray magnetic flux, is provided in a position where the said switching means receives the stray magnetic flux developed by existence of a gap or gaps between the armature and the stator core.

The said winding and the stator core form an electromagnet to attract the said movable armature to the core when the magnetic flux is generated by an exciting current in the winding. Switch contacts of the circuit, or a mechanical means, such as a ratchet to be driven thereby, can be linked to the said movable armature. A reed switch, or a magnetically responsive semiconductor device, can be employed as the said magnetically responsive switching means. The term reed LII The invention, both as to construction and operation, together with additional objects and advantages thereof, will be best understoodv from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a top plan view of a relay constructed in accordance with one embodiment of the present invention;

FIG. 2 is a side elevation view of the relay shown in FIG. 1;

FIG. 3 is a circuit diagram of an electromagnetic device embodying the present invention;

FIG. 4 is another circuit diagram of an electromagnetic device embodying the present invention;

FIG. 5 is a side sectional view of another relay constructed in accordance with another embodiment .of the present invention; and 1 FIG. 6 is a side sectional view of still another relay constructed in accordance with another embodiment of the present invention. I

The electromagnet device shown in FIG. 1 and FIG. 2 relatesto a hinge-type relay.

. Referring to the constructional details shown in FIG. 1 and I FIG. 2, an armature 1 made of iron is provided movably at a switch in this description denotes a magnetically responsive switching means comprising at least one pair of reed contacts of magnetic metal, of which at least one is resilient so as to enable it to be attracted by and contact and other reed contact when the magnetic flux surrounds them, and an airtight enclosure for enclosing the reed contacts. The said magnetically responsive semiconductor device is a semiconductor device which performs a switching action in response to a change in the surrounding magnetic flux. The magnetically responsive switching means responds to a decrease of the stray magnetic flux caused by touching of the armature to the core, and switches the electric circuit of the said winding to reduce the ampere turns of the winding to a low value just sufficient to hold the already attracted armature in its set position. Thus,

supporting portion 2 of a supporter plate 3 made 'of iron. The supporter plate 3 is fixed upon the outer surface of a standing leg 4 of a yoke 5 made of iron, a cylindrical core 6 made of iron is fixed on the yoke 5, and a coil 7 is wound on a spool 8 enclosing the core 6. A terminal board 9 bearing terminals 10 is fixed to another standing leg 11 of the yoke 5.

Arms 12 of thin elastic metal plate, comprising contacts 13 and 13 on their moving ends, are fixed in aninsulated state upon the armature l. A tension spring 14 is provided between a hook part 15 of the supporter plate 3 and a hook part 16 of the armature 1 in order to impart to the armature l a force to separate the armature from the core 6 by pivoting it about the supporting portion 2. Fixed contacts 17 and 17 positioned to contact the contacts 13 and 13', respectively, are provided on the terminal board 9. Near a gap 19, which is formed between the armature 1 and the core 6 when they 'are apart, is provided a reed switch 18 for controlling the ampere turns of the coil.

The reed switch 18 can be located in any place where it will receive the stray magnetic flux which is formed during the period after the current has been fed to the coil 7 and before the armature l is attracted to the core 6.

The electrical configuration of the said relay can be provided in either way as shown in FIG. 3 or FIG. 4.

Referring to the circuit diagram shown in FIG. 3, a first winding 71 and second winding 72 constitute the coil 7 referred to in FIG. 1 and FIG. 2. The first winding 71 is connected directly across terminals 20 and 21 which lead to a DC power source 22 through a switch 23. The second winding 72 and the reed switch 18 are connected in series between the terminals 20 and 21. Elements for extinguishing surge currents and suppressing arcs, such as a resistor 25 and a capacitor 26,

are connected in series across the contacts of the reed switch is open from the beginning. In this stage, i.e., just after the closing of the switch 23, the armature 1 is not yet attracted to the core 6, on account of the insufficiency of the magnetic flux, while the reed switch 18 operates and closes the circuit of the second winding 72, in response to the straymagnetic flux existing around the gap 19 between the armature l and the core 6, thereby closing a current path through the second winding 72. The current in the second winding 72, together with the current in the first winding 71, generates a large magnetic flux, and consequently, the armature 1 is attracted to the core 6. Upon attraction of the armature 1 to the core 6, the stray magnetic flux vanishes, and therefore, the reed switch 18 is opened, thus extinguishing the current through the second winding 72 and thereby reducing the magnetic flux to a low level just sufficient for keeping the armature l in'touch with the core 6. Thus, after the setting of thedevice, i. e.,' setting of the armature l in a position contacting the core 6, the total current fed tothedevice is considerably decreased; thereby lowering the power consumption of the device.

FIG. 4 is a circuit diagramiexhibitin'g another example of a circuit connection applicable to the relay illustrated in FIG. 1

and FIG. 2.

Referring to FIG. 4*, "a .winding 73 constitutesthe coil 7 shown in FIG. 1 and FIG. 2. The winding 73 and a currentrestricting resistor 24 areconnected in series between terminals and 2lwhich lead to-a DC power source 22 through a switch 23. The reed switch 18 is connected in parallel with the resistor 24.

The relay having a construction as described referring to FIG. 1 and FIG/2 as well as a connection as described referring to FIG. 4 operates as follows:

Upon closing of the switch 23, a current flows from the power source 22 tothe winding 73 through the resistance 24,, as the reed switch 18 is open from the beginning. In this stage,

i.e., just after the closing of the switch 23, the armature l is not yet attracted to the core 6, on account of the insufficiency tion of the resistor 24 in series to the winding 73 and reducing the magnetic flux to a low level just sufficient to keep the armature l in contact with the core'6. Thus, after the setting of 1 device.

The electromagnetic device shown in connection with FIG. 5 relates to an example of a plunger-type relay.

Referring to the construction details shown in FIG. 5, an E- shaped stator core 31 is fixed on the bottom of a box-type housing 32. A coil 33 is wound on the spool 34 fixed around the center leg 35 of the core 31. An E-shaped movable armature 36 is provided to face opposite the core 31, being supported by pressure springs 37 so as to impart to the armature 36 a force to separate it from the core 31. In a hollow 38 of the spool 34, located near the gap 49 between the core'31 and the armature 36, a reed switch 48 is provided. The contact carrier 39 is-connected with the armature 36 by a connecting pin 40. In a space 45 under a cover 46, a transverse contact plate 41 bearing contacts 43 issupported in a hole 42 of the contact carrier 39, being biased by a pressure spring 44. In the space 45, fixed contacts 47 are provided opposite the said contacts 43; t I

The electrical circuit arrangement of the said device can be provided either as shown in FIG. 3 or FIG. 4. Therefore, the explanations already set forth as regards FIG. 3 and FIG. 4 are fully applicable by substituting the reference numerals as follows:

coil 33 for coil reed switch 48 for reed switch 18 armature 36 for armature 1 core 31 for core 6 gap 49 for gap 19 The electromagnetic device shown in connection with FIG. 6 relates to another example of a plunger-type relay.

Referring to the constructional details shown in FIG. 6, a reed switch 51 is provided in a hollow 52 located in a sidewall of the housing and near the gap 49 which is formed between the core 31 and the armature 36. The remaining part is constructed in the same manner as described with reference to FIG. 5. The electrical constitution of this relay can be made in either way as shown in FIG. 3 or FIG. 4. The explanations already set forth as regards FIG. 3 and FIG. 4-are fully applicable by substituting the reference numerals as follows:

coil 33 for coil 7 reed switch 51 for reed switch 18 armature 36 for armature 1 core 31 for core 6 gap 49 for gap 19 I The reed switches of the above-mentioned examples may be delayed-setting-type reed switches tilled with viscous fluid. In an electromagnetic device comprising such viscous-fluid-filled reed switch, the reed switch closes after a lapse of a specific delay period, and therefore, the setting of the device is delayed. Thus, a delay time within several seconds in the setting operation is easily obtainable.

The electromagnetic device of the present invention can be constructed to have a smaller coil as compared with-conventional devices because contacts hitherto provided on the armature for controlling the current after setting of the device is replaced by a magnetic sensitive switching means, and therefore, the necessary force to attract the armature to the core can be reduced by the extent hitherto required to press the contacts to touch each other. I

In the electromagnetic device of the present invention, adjustment of the operation of the device, such as adjusting the sensitivity of the magnetic sensitive switching means, can be easily accomplished by adjusting the location and slant of the reed switch.

The electromagnetic device of the present invention has a great reliability on account of the use of a reliable reed switch.

In addition, in a relay embodying the present invention, all of the contacts provided on its armature can be employed for a switching circuit which is independent from the circuit of this relay, because the circuit of this relay is not connected to any of the contacts provided on the armature. That is to say, the relay embodying the present invention can be made smaller than the conventional one possessing the same number of contacts. Thus, the relay embodying the present invention can be made to possess more contacts in comparison with a conventional relay having a similar size.

Furthermore, a delayed setting operation is obtainable by employing a delayed-setting-type reed switch in an electromagnetic device of the present invention.

We claim:

1. An electromagnetic device comprising at least one winding for generating a magnetic flux in response to a current applied through a circuit from an energizing source thereto, a

' stator core magnetically coupled with the said winding, a

movable armature which is attracted to the core when a maximum level of magnetic flux is generated and held in contact with said core when a minimum level of magnetic flux is generated, at least one magnetically responsive means connected with the circuit supplying current from said source to said winding and responsive to said magnetic flux for switchably controlling the current applied to said winding to adjust said magnetic flux from a minimum level to a maximum level, said switching means being positioned to receive the stray magnetic flux developed by existence of a gap between the armature and the stator core.

2. An electromagnetic device as defined in claim 1, wherein the said magnetically responsive switching means is in series with said winding and comprises at least one pair of reed con-' tacts of magnetic metal, of which at least one is resilient so as to enable it to be attracted by and contact the other reed contact when a magnetic flux surrounds them, and an airtight enclosure for enclosing the reed contacts.

3. An electromagnetic device as defined in claim 2, wherein an arc-suppressing circuit consisting of at least one resistor and at least one capacitor is connected across the contacts of said magnetically responsive switching means.

4. An electromagnetic device as defined in claim 2, wherein the airtight enclosure is filled with a viscous fluid.

' the stator core and the armature form a plunger-type electromagnetic device, and the said magnetically responsive switching means is placed in a hollow formed in a wall of a housing which encloses the said core, said armature and said winding, said switching means being connected in series with said winding and comprising at least one pair of reed contacts of magnetic metal of which at least one is resilient so as to enable it to be attracted by and contact the other reed contact when a magnetic flux'surrounds them, and an airtight enclosure for enclosing the reed contacts.

8. An electromagnetic device as defined in claim 7, wherein an arc-suppressing circuit consisting of at least one resistor and at least one capacitor is connected across the contacts of the magnetically responsive switching means.

9'. An electromagnetic device as defined in claim 1, wherein the said magnetically responsiveswitching means is placed in a hollow formed in a spool of the winding 10. An electromagnetic v device as defined in claim --l, wherein the stator core and the armature form a plunger-type electromagnetic device and the said magnetically'responsive switching means is placed in a hollow formed in a wall of a housing which encloses the said core, said armature and said winding. 

1. An electromagnetic device comprising at least one winding for generating a magnetic flux in response to a current applied through a circuit from an energizing source thereto, a stator core magnetically coupled with the said winding, a movable armature which is attracted to the core when a maximum level of magnetic flux is generated and held in contact with said core when a minimum level of magnetic flux is generated, at least one magnetically responsive means connected with the circuit supplying current from said source to said winding and responsive to said magnetic flux for switchably controlling the current applied to said winding to adjust said magnetic flux from a minimum level to a maximum level, said switching means being positioned to receive the stray magnetic flux developed by existence of a gap between the armature and the stator core.
 2. An electromagnetic device as defined in claim 1, wherein the said magnetically responsive switching means is in series with said winding and comprises at least one pair of reed contacts of magnetic metal, of which at least one is resilient so as to enable it to be attracted by and contact the other reed contact when a magnetic flux surrounds them, and an airtight enclosure for enclosing the reed contacts.
 3. An electromagnetic device as defined in claim 2, wherein an arc-suppressing circuit consisting of at least one resistor and at least one capacitor is connected across the contacts of said magnetically responsive switching means.
 4. An electromagnetic device as defined in claim 2, wherein the airtight enclosure is filled with a viscous fluid.
 5. An electromagnetic device as defined in claim 2 wherein a second winding capable of generating only said minimum level of magnetic flux is connected across the series combination of said one winding and said magnetically responsive switching means.
 6. An electromagnetic device as defined in claim 2 wherein a current-limiting resistor is connected across the contacts of said magnetic responsive switching means.
 7. An electromagnetic device as defined in claim 1, wherein the stator core and the armature form a plunger-type electromagnetic device, and the said magnetically responsive switching means is placed in a hollow formed in a wall of a housing which encloses the said core, said armature and said winding, said switching means being connected in series with said winding and comprising at least one pair of reed contacts of magnetic metal of which at least one is resilient so as to enable it to be attracted by and contact the other reed contact when a magnetic flux surrounds them, and an airtight enclosure for enclosing the reed contacts.
 8. An electromagnetic device as defined in claim 7, wherein an arc-suppressing circuit consisting of at least one resistor and at least one capacitor is connected across the contacts of the magnetically responsive switching means.
 9. An electromagnetic device as defined in claim 1, wherein the said magnetically responsive switching means is placed in a hollow formed in a spool of the winding.
 10. An electromagnetic device as defined in claim 1, wherein the stator core and the armature form a plunger-type electromagnetic device and the said magnetically responsive switching means is placed in a hollow formed in a wall of a housing which encloses the said core, said armature and said winding. 